1. Field of the Invention
The present invention relates to thermoplastic polyurethane textures, and more particularly to a method for the surface treatment of thermoplastic polyurethane textures with laminated deep and shallow impressions.
2. Description of the Related Art
The flexibility of PVC can be changed by way of an added plasticizer, and so manufacturers can easily create products with various flexibilities and shapes which are commonly found. However, PVC has poor high thermal resistance, poor flex resistance and poor impact absorption. Furthermore, dioxin, chlorine, heavy metal particulates and such poisonous substances are produced when products are disposed in high thermal environments or burned, and these toxins severely threaten our daily life and health. Therefore, with recent rise in environmental awareness, environmental materials are preferred for the production of products; for example, TPU is substituted for PVC.
To be specific, TPU is a kind of macromolecule elastomer provided with no plasticizer, and its physical properties are between rubber and plastic. When present as a rubber/plastic material, TPU provides wear resistance, flex resistance, high tensile, high tear strength and resistance to low temperatures, and it is also a form of non-toxic, environmental material, and so it can be extensively applied to shoes, sporting goods, clothing, medical supplies and so on.
With technological advances, consumers not only have requirements for product specifications and functions, but also care about product appearance when shopping. Taking the casing of a consumer electronic product for example, manufacturers usually print impressions onto the surface of the casing, which provides unique patterns and feelings to attract the consumers' attention.
Please refer to FIG. 1, which concerns Taiwan Invention Patent No. I392592, entitled “Apparatus for Pattern Replication with Intermediate Stamp”, which operates mutually and simultaneously to perform a second step. In the first transfer printing unit, the impression duplication of a template 11 is formed in or on an intermediate disk, or to be better formed in or on a flexible polymer foil 13 by a transfer printing unit to obtain an intermediate stamp, and the polymer foil 13 is made from thermoplastic polymer, thermosetting polymer, or polymer. The intermediate stamp is moved from the first transfer printing unit to the second transfer printing unit, and in the second transfer printing unit, the intermediate stamp is utilized to transfer print the impression onto the moldable layer of a substrate 12 target surface by a second step.
From the above descriptions, certain problems still exist in the prior art method:
1. Increased Defect Rate in the Process
The impression structure on the surface can be transfer printed onto the flexible polymer foil 13 by the template 11 to form a decorated impression on it. However, the above surface decoration technique is mostly utilized to decorate the surface only once; if the technique is repeated a second time, the existing decorated impression will be damaged and the defect rate will be increased in the process.
2. Complicated, Time-wasting Process
The prior art utilizes a double transfer printing process, and the transfer printing process of the second surface is performed after the first one has solidified. Therefore, this kind of process wastes time and resources.
3. No Enhancement of Visual Impressions
The embossment is only able to be formed on the surface of the flexible polymer foil 13 by the template 11, but no vertical side decorative impressions can be formed, and so there is no 3D stylish decoration effect. Therefore, it cannot meet consumer requirements for visual impressions.
The above disadvantages express the problems of the current apparatus for pattern replication with intermediate stamp. Therefore, it is desirable to provide a device which can improve the present disadvantages in processing, or to provide a design for improving product yield rates, while enhancing the visual impression to satisfy the consumer requirements, and obtain competitive advantages in the market.